SOME developmentsREGARDING functional FOOD PRODUCTS
(functional foods)
Raquel de Pinho Ferreira Guiné* and Maria João Reis Lima
CI&DETS / ESAV (Department of Food Engineering)
Polytechnic Institute of Viseu,
Quinta da Alagoa, Estrada de Nelas, Ranhados, 3500-606 Viseu
Telf: + 351 232 446600, Fax: + 351 232 426 536
*E-mail:
Disclosure
This manuscript is an extended and updated version of the previously published: Guine RPF and Lima MJR (2008) Overview and Developments Regarding Functional Foods and Beverages. Current Nutrition & Food Science, 4(49), 298-304.
Abstract
More and more functional foods or nutraceuticals have proved to be important allies both to health promotion and disease treatment. For these reasons many research has been going on aimed at identifying functional components in foods and relate them with positive physiological effects. Although there is a distinction between what is a functional food and a nutraceutical, the truth is that these two concepts are much related. In fact, both nutraceuticals and functional foods are foods, or dietary components, that provide some health benefit beyond basic nutrition. However, while functional foods aim at providing some health benefit in general, the nutraceuticals go further beyond, and include aspects such as the effective prevention or treatment of disease.
Recent research continues to support many findings that seem to validate the benefits of foods or food components to the promotion of health. It has been widely stated that people who consume a wide variety of foods containing some bioactive molecules like carotenoids, fibers, flavonoids, fatty acids, phytoestrogens, vitamins and minerals, among others, show a reduced risk of developing some diseases and tend to have a better health. As an example, the use of antioxidants provides protection against harmful free radicals, usually associated with cardiovascular disease, cancer, diabetes, Alzheimer’s disease and age-related functional decline. Also the ingestion of dietary fibres has been related to improvement in gastrointestinal functions, as well as a reduced risk of developing colorectal cancer.
The present workgivesa general overview of functional foods, pointing out examples of some foods with a recognized functional ability,as well as leaving some clues about new developments in this field.
Keywords: functional food, nutraceutical, functional component, bioactive molecule, health, diet.
1. Introduction
Functional foods research is gaining importance because the interest in nutrition as a positive force for health is largely growing within today’s society. Functional food is any fresh or processed food that is claimed to have a health-promoting and/or disease-preventing property beyond the basic nutritional function of supplying nutrients. In this way, these foods may help prevent disease, reduce the risk of developing disease, or enhance health [1].
Nowadays, functionalfoods represent one of the most interesting areas of research and innovation in the food industry [2].The functionalfoods represent a new category of products that promise consumers improvements in targeted physiological functions [3]. Vascular biology is of critical importance for initiation and perpetuation of hypertension and target organ sequelae. Possible factors that may initiate hypertension are endothelial activation, oxidative stress and vascular smooth muscle. Nutrient-gene interactions determine a broad array of phenotypic consequences such as vascular problems and hypertension. In this way, optimal nutrition, nutraceuticals, vitamins, antioxidants, minerals, weight loss, exercise and smoking cessation [4] will allow achievinglow blood pressure levels, thus giving place to a lot of consequences, such as: reducing cardiovascular risk factors, improvingvascular biology, reducing organ damage, congestive heart failure and renal disease. It has been shown that a combination of macro and micronutrients conjugated with a good lifestyle influences both mental and physical health.
At present many food componentsare considered to have special and specific beneficial effects for human health, and consequently, considerable attention has been given to studies focusing this reality all over the world. The list of potential health substances is, therefore, continuously growing, and includes a wide variety of substances that are recognized to have a positive role in the pathogenesis of many diseases such as aging, cancer, cardiovascular disorders and diabetes[5].The term functional food is related to health-promoting dietary components beyond traditional nutrients, which play an important role in enhancing human health. This perspective has been in human mind since the 1920s with the discovery that some fatty acids had an important role in people’s health. This concept has been conceived in Japanese initiatives in the 1980s sparked by government policies to improve health [6]. The resulting list of the actually established bioactive compounds is constantly growing and includes many metabolites that can be produced by microorganisms.
The effects of food and nutrient intake and their relation with different types of cancer has been widely studied [7,8]. Many epidemiological studies have suggested associations between diet and cancer,either in the case of foods that enhance cancer development (such as trans fatty acids) or prevention (like vegetables and fruits).Functional foods and nutraceuticals stand in the group of foods associated to cancer prevention and some examples include fruits, vegetables, whole grains, fortified or enhanced foods, beverages and dietary supplements. Functional attributes of many traditional foods are being discovered and consolidated, as well as their health effects. Furthermore, an increasingnumber of food products are also being developed by incorporating beneficial components, which are designed to confer target specific health benefits.
Nowadays the relationship between diet and health becomes an important request for the consumer and the demand for information about functional food has increased. For example, certain functional foods and vitamin supplements have been developed to provide consumers with nutrients that may be lacking in some people’s diets, or that the body is unable to produce and may occur in insufficient levels in the food supply [9].
Some scientific research has been published in the past decades, with the purpose of demonstrating the clinical and potential bioavailability and absorption of bioactive compounds. This has lead many regulatory organizations to consider ways for the establishment of the scientific basis that support and validate claims for functional foods. Differences in educational and professional background and level of proficiency in nutrition may also affect beliefs about functional foods[10].It is generally accepted thata healthy diet is one of the most important ways of enhancing health[11].
Nowadays several socio-economic factors have a very pronounced influence on diet composition, and these may include aspects such as culture, personal preference, price, availability or convenience, besides environmental, social or health concerns [12]. People consume not only to fulfill their basic biological needs, but also to express a sense of self and improve psychological well-being. People’s behavior towards food selection is presently strongly influenced by health and fitness preoccupations, cultural and ethical concerns, and worries about animal welfare or political and moral standpoints. Indeed, the social consequences of consumption are becoming more important every day [12].
It is not a neglectable aspect that functional food products help to ensure an overall good health and/or to prevent/manage specific conditions in a convenient way [13]. Furthermore, persuading people to make healthier food choices could be an important way to achieve substantial public health effects such as decreased mortality or increased quality of life [13].
2. Identification and health benefits
2.1. Role of diet in enhancing human health
The market for functional foods is currently increasing and includes a variety of foods, such as those lowering blood cholesterol or blood pressure, and foods advancing the well-being of the stomach or the prevention of caries. Typically, a food marketed as functional contains added, technologically developed ingredients with a specific health benefit [11].
Functional foods can have two primary effects on health: the enhancement of physiological functions and the reduction of disease risk and eventually therapy [14].The functioning of the immune system and its role in protecting the host is continuously revaluated, namely the balance between pro and anti-inflammatory effects, inter-individual variations and available biomarkers [14]. Studies conducted both on animals and humans have demonstrated that optimizing food intake through nutrient fortification can restore resistance to infections; however, excesses can also lead to impaired immune function.
In modern societies food consumption is characterized by multiple developments that make eating an increasingly complicated sphere of life. One of these developments is related to health, which plays an important role in contemporary discussion of food. The ingestion of a healthy diet is viewed as one of the most important means of health promotion in political programs and strategies and also in public discussion[11]. Both research areas: nutrition and biomedical, are working together in both fields so as to produce an increasingly detailed knowledge of correlations between nutrition and health.
In the last decades, considerable worldwide attention has been given to functional foods since the bioactive substances have demonstrated benefits in many aspects related to health. For example, lycopene, a carotenoid found in tomato products, prevents oxidation of low density lipoprotein (LDL) cholesterol and reduces the risk of developing atherosclerosis and coronary heart disease [15, 16].
Soluble fibers lower serum cholesterol by reducing the absorption of dietary cholesterol. Furthermore, low blood cholesterol levels are associated with a lower risk of developing coronary heart disease [17], and are also tightly related to the diminishing in the occurrence of cardiovascular disease [18].
Several researches indicate that an intake of essential fatty acids is beneficial for those suffering from rheumatoid arthritis, also reducing tenderness in joints, swelling and morning stiffness. In addition, some studies suggest that diets rich in omega-3 fatty acids (and low in omega-6 fatty acids) may benefit people with other inflammatory disorders such as osteoarthritis [15].
The intake of plant sterols has proved to be inversely associated with many different types of cancer, namely: breast [19], prostate [20], lung [21], esophagus [22], stomach [23], endometrial [24] and ovary [25].
The possibility of applying genomic tools to study the integrated effects of nutrients on gene regulation, namely nutrigenomics, presents great promise in clarifying or increasing the understanding and knowledge of how nutrients affect the whole organism in health and disease [26]. In fact, several authors share the opinion that the particular susceptibility to the diet is dependent of genetic polymorphisms.
2.2. The different functional food components
Functional food components are potentially beneficial components found naturally in foods or added to them as functional ingredients, and include carotenoids, dietary fiber, fatty acids, flavonoids, isothiocyanates,phenolic acids, plant stanols and sterols, polyols, prebiotics and probiotics, phytoestrogens, soy protein , vitamins and minerals.
Probiotics are living microorganisms including Lactobacillus species, Bifidobacterium species and yeasts, which, if ingested in certain amounts have a positive health impactby improving the balance of the intestinal microflora. Probiotic bacteria are typically chosen from the safe bacteria that normally inhabit the gastrointestinal system of humans. It has been proved that certain strains consumed at adequate levels positively influence human health, namely concerning diarrhea [27], irritable bowel syndrome [28], inflammatory bowel disease [29], hypertension [30], cancer [31] or immune system stimulation [32], among others.
The term prebiotic is applied to food ingredients that may have a positive impact in the host by the improvement of the intestinal flora. These are nondigestible, reaching the colon where they stimulate the growth and/or the activity of some bacteria. The positive effects of prebiotics include antimicrobial, anticarcinogenic, hypolipidemic, glucose-modulatory and anti-osteoporotic activities. They may be used for the treatment of constipation, hepatic encephalopathy and inflammatory bowel disease [15].
The term synbiotic is used for products that contain both probiotics and prebiotics. Such products take advantage of both the addition of beneficial bacteria and the encouragement of the growth of resident beneficial bacteria. Among the various positives effects of synbiotics, are the antimicrobial, anticarcinogenic, antidiarrheal and antialergenic qualities, the prevention of osteoporosis, the reduction of serum fats and blood sugars, the regulation of the immune system and the treatment of the liver-related brain dysfunction [15].
Carotenoids are a class of fat-soluble natural occurring pigments found mostly in plants, fruits, flowers, algae, and photosynthetic bacteria. Carotenoids play an important function in human health and for example the role of beta-carotene and others as the main dietary source of vitamin A has been known for many years. More recently, protective effects of carotenoids against serious disorders such as cancer [33], heart disease [16] and degenerative eye disease [34] have been recognized, and have stimulated intensive research into the role of carotenoids as antioxidants and as regulators of the immune response system.
Dietary fiber is one of the nutrients most associatedto health promotion and disease prevention. The consumption of dietary and functional fibers is correlated to health benefits such as the ability to lower cholesterol, prevent obesity and diabetes, avoid colon cancer [35], and diminish the incidence of coronary and cardiovascular heart diseases [36].
Essential fatty acids (EFAs) are long-chain polyunsaturated fatty acids which play an important role on human health promotion. However, since they cannot be synthesized by the human body it is necessary to obtain them through diet. They are “good fats” that compete with “bad fats”, such as trans fats and cholesterol. On the other hand, good fats raise the levels of high density lipoprotein (HDL), or "good cholesterol", which grabs the bad cholesterol, LDL (low density lipoprotein), escorting it to the liver where it is broken down and excreted. In general terms, the EFAs are related to many beneficial effects on the human health. By their role in the cell membranes, they help in the absorption of essential nutrients and expelling of harmful waste products. They support the cardiovascular, reproductive, immune, and nervous systems, and are important for proper growth in children, particularly for neural development and maturation of sensory systems. Besides, EFAs increase the production of prostaglandins, which regulate body functions such as heart rate, blood pressure, blood clotting, fertility, conception, and play a role in immune function by regulating inflammation and encouraging the body to fight infection [37].
Sterols and stanols are found naturally in various plants such as fruits, vegetables, nuts, seeds, cereals, legumes and vegetable oils, among others. Both stanols and sterols are essential components of plant cell membranes and structurally resemble cholesterol, which itself is also a sterol, but, unlike plant sterols, it is predominantly of animal origin. In the human body, strerols and stanols have a potential for lowering blood cholesterol and they are associated toa reduction in the absorption of cholesterol by the human intestine. Besides their cholesterol lowering effect, plant sterols also have other positive activities, such as anti-inflammatory, anti-oxidative, anti-atherosclerosis and anti-cancer [38].
Phytoestrogens (PEs) are naturally occurring plant compounds similar to estrogenic hormones. These have many physiological effects in the metabolism of carbohydrates, proteins, lipids and minerals in the human body, besides having an essential role in the reproductive cycle in women. Estrogens are used to avoid contraception and as a therapy for women at menopause. On the other hand, there are compounds used to treat infertility and to control breast cancer, which, by exerting an opposite effect to that of the estrogens, are called antiestrogens [39].
Among dietary proteins, soy protein is considered a complete protein, since it contains large amounts of all the essential amino acids and many other macronutrients with a nutritional value roughly equivalent to that of animal protein of high biological value [40]. Soy protein showed some chemo-preventive activity, as reported by Xiao et al. [41].
Flavonoids are a large family of polyphenolic compounds, synthesized by plants, acting as pigments responsible for many of the bright colors of vegetables, fruits and flowers [42]. Flavonoids act in the human body in many different ways. For example, in some cases, they act as antibiotics, by interfering directly in the functioning of certain microorganisms like bacteria [43] or viruses [44]. In some other cases, flavonoids alter the behavior of cells of the immune system, thus preventing excessive inflammation [45]. However, most flavonoids act in the human body as antioxidants, protecting cells against the damaging effects of reactive oxygen species [46]. An imbalance between antioxidants and reactive oxygen species causes cellular damage due to oxidative stress, which has been linked to a number of diseases like cancer, atherosclerosis, ischemic injury, inflammation, and aging related pathologies, such as neurodegenerative diseases (Alzheimer’s and Parkinson’s).
Phenolic acids are plant metabolites widely distributed in plants that have shown a potential protective role against oxidative damage diseases, such as coronary heart disease, stroke, and cancers [47].
Polyols, also called sugar alcohols, are a group of low calorie, carbohydrate-based sweeteners, commonly added to foods [48]. Polyols present a similar taste and texture to sugar, but they offer some important health benefits, which include the maintenance of good oral health, aiding in weight loss or weight maintenance, and reducing overall dietary glycemic load [49]. Besides, they may also play a role in the maintenance of human digestive health [50].
Isothiocyanates are a group of sulphur-containing phytochemicals, which includes a wide number of different molecules. Isothiocyanates occur naturally as glucosinolate conjugates in cruciferous vegetables such as broccoli, cauliflower, kale, Brussels sprouts, cabbage, and others. Studies have shown that isothiocyanates and their metabolites help to lower the risk of developing different types of cancer, namely lung, breast, liver, esophagus, stomach, small intestine and colon [51].